Rare Sept. 11 aerial photos released

This photo taken Sept. 11, 2001 by the New York City Police Department and obtained by ABC News, which claims to have obtained it under the Freedom of Information Act, shows smoke billowing from one of the towers of the World Trade Center in New York. (AP Photo/NYPD via ABC News, Det. Greg Semendinger) MANDATORY CREDIT

This photo taken Sept. 11, 2001 by the New York City Police Department and obtained by ABC News, which claims to have obtained it under the Freedom of Information Act, shows smoke and ash engulfing the area around the World Trade Center in New York. (AP Photo/NYPD via ABC News, Det. Greg Semendinger) MANDATORY CREDIT

? Aerial photos of the World Trade Center — including these images of the north tower and surrounding area — were released this week, offering a rare and chilling view of the twin towers and the shroud of smoke and dust that settled over New York City.

The images were taken from a police helicopter — the only photographers allowed in the airspace near the skyscrapers on Sept. 11, 2001. They were obtained by ABC after it filed a Freedom of Information Act request last year with the National Institute of Standards and Technology, the federal agency that investigated the collapse.